Dual-Function Antenna Circuit for Microwave Tamper Detection
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Solution Overview
Problem
Conventional security elements in valuable documents, such as passports and identity cards, are vulnerable to falsification when the RFID microcircuit is rendered inoperative by microwave radiation, making it difficult to detect fraud as the document appears undamaged.
Innovation Solution
A security system that includes a dual-function antenna circuit with a dipole and magnetic loop antenna, optimized for both near-field and far-field microwave radiation regions, which accelerates a chemical reaction in an active substance upon exposure to microwave radiation, causing a visible change that indicates microcircuit destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-function antenna is used to pick up microwave radiation, then the device complexity is reduced, but the ability to efficiently detect microcircuit destruction is insufficient
Solution Approach 1:
The antenna circuit is segmented into two distinct antenna parts: a first antenna part for picking up electric component of microwave radiation and a second antenna part for picking up magnetic component. This segmentation allows each part to be optimized for its specific function, improving overall detection reliability while maintaining manageable complexity through functional specialization.
Solution Approach 2:
The antenna circuit is designed with multi-functionality by incorporating both electric and magnetic component pickup capabilities within a single integrated circuit structure. This universal design enables the antenna circuit to efficiently detect microcircuit destruction across different microwave radiation conditions without requiring separate detection systems.
2Reliability
If conventional security elements are used alone, then the device complexity is reduced, but the security against falsification is insufficient when RFID device fails
Solution Approach 1:
The security system incorporates a preliminary detection mechanism that activates before complete microcircuit destruction occurs. The antenna circuit and active substance are positioned to detect microwave radiation effects in advance, triggering a visible change that prevents falsification attempts before they can succeed, thereby maintaining high security reliability.
Solution Approach 2:
The security system utilizes an active substance that undergoes a visible color change when exposed to microwave radiation. This color change provides a clear visual indicator of microcircuit destruction or tampering attempts, enhancing security reliability by making falsification detectable without requiring complex detection equipment.
3Reliability
If the microcircuit is exposed to microwave radiation for a predefined duration, then the microcircuit is rendered inoperative, but the detection time is extended
Solution Approach 1:
The antenna circuit performs preliminary detection of microwave radiation exposure before the microcircuit is completely destroyed. By detecting the presence of microwave radiation and the resulting temperature increase in the active substance, the system can alert users before the full destruction process completes, significantly reducing detection time while maintaining microcircuit security.
Solution Approach 2:
The security system incorporates a feedback mechanism where the antenna circuit continuously monitors the microcircuit's response to microwave radiation. When temperature increase is detected through the active substance, the system provides immediate feedback, enabling rapid detection and response before complete microcircuit failure occurs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid detection of microcircuit destruction within the document, enhancing security by visibly indicating tampering attempts, thus preventing fraudulent use of the document.
Implementation Method 1
a first antenna part (48) arranged to essentially pick up an electric component (E) of the microwave radiation
Implementation Method 2
a second antenna part (50) arranged to essentially pick up a magnetic component (H) of this radiation
Implementation Method 3
a load (46) extending at least partially in the predefined zone (Z), connected to the antenna element and able to heat up when a current passes through it
Implementation Method 4
an active substance (40) capable of changing color irreversibly by a chemical reaction triggered by exposure to microwave radiation
Implementation Method 5
a catalyst element capable of making the chemical reaction at the origin of the color change total and effective
Data Source
Figure 1~5
Figure 2~3
AI summary
The system comprises a device for revelation of powerful microwave radiation exposure of a microcircuit. The device comprises a unit, which is sensitive to an elevation of temperature of a predefined area in a valuable document (10), and an antenna circuit comprising an antenna element significantly tunes in microwave radiation and a charge that partially extends in the predefined area, is connected to the antenna element and is capable of heating when it is crossed by a stream. The antenna element comprises a first part of antenna to capture an electrical component in microwave radiation. The system comprises a device for revelation of powerful microwave radiation exposure of a microcircuit. The device comprises a unit, which is sensitive to an elevation of temperature of a predefined area in a valuable document (10), and an antenna circuit comprising an antenna element significantly tunes in microwave radiation and a charge that partially extends in the predefined area, is connected to the antenna element and is capable of heating when it is crossed by a stream. The antenna element comprises a first part of antenna arranged to capture an electrical component in microwave radiation, and a second part of antenna arranged to capture a magnetic component from the radiation, where the first part of the antenna is a dipole antenna and second part of antenna is a magnetic loop antenna. The first antenna part comprises two electrically conducting branches separated by a dielectric, and the second antenna part comprises electrically conductive coils. The dipole antenna has a length, which is less than half of the wavelength of microwave radiation. The antenna circuit further comprises an interface for mutually coupling the first and second parts. The coupling interface comprises an electrically conductive element connected to the first part of the antenna and partially connected to the second part of the antenna. The antenna element is made by screen printing with electrically conductive ink. The sensitive unit is arranged to undergo a detectable transformation under the effect of an elevated temperature, and comprises a color changing substance passing from a first stable state to a second stable state by chemical reaction triggered by the microwave radiation, where the reaction is to be rendered effectively and completely by raising the temperature. The second part of antenna is connected to the charge. The first and second parts of the antenna are sized to carry out an impedance matching. The microcircuit is inoperative by exposure to the microwave radiation of a predefined power of greater than 50W and a preset time of 0.1-10 seconds. An independent claim is included for a valuable document.